Plastic fasteners of the type commonly used for consumer goods, for example attach merchandise tags to article of commerce, such as article of clothing, and may also be used in automotive packaging and electrical applications as well. Typically, fasteners are mass-produced into one of two different forms known as fastener stock. One type of fastener stock comprises a plurality of fasteners joined together at their respective cross-bars by an orthogonally disposed runner bar. The other type of fastener stock comprises a plurality of fasteners arranged in an end-to-end alignment, the ends of successive fasteners being joined together by severable connectors so as to form a length of continuously connected fastener stock.
A common type of fastener assembly is a cable tie having a head, a strap and a tail. The head portion of a cable tie generally has a pawl portion. Another type of fastener assembly is of the type which includes an elongated flexible filament having a first cross-bar at one end and a paddle or a second-cross-bar at the opposite end.
One type of common problem with fasteners, particularly cable ties, is that under high loop tensile force, the head portion of the fastener slips. For instance, when the strap of the cable tie is inserted into the head of the cable tie and cinched around an object, such as an article of merchandise or automotive wires, the pawl of the head portion of the cable tie pivots and the ratcheting teeth on the pawl engage with teeth on the strap of the cable tie. The potentially weak aspect of the fastener, such as the cable tie, is typically in the pawl such that when the loop tensile load increases, the pawl feature of the head portion of the cable tie flexes and distorts. The main failure for fasteners currently in the marketplace is referred to as “pawl roll out” which is when the pawl rotates out of the head portion of the fastener assembly and disengages from the teeth on the strap of the fastener assembly causing the fastener to release.
Another problem with the fasteners currently available in the market place, is that increasing the loop tensile strength of a cable tie requires increasing the size of the pawl feature of the head portion of the cable tie, which, in turn, requires an increase in the cross section of the cable tie strap and the overall size of the head. This design approach requires more material usage and thus, increases the cost to manufacture the product. A still further design approach currently in use in the marketplace to increase loop tensile strength is to increase the strap tooth depth. This requires more material usage and requires the user of the cable tie to use more force when cinching the strap around an article. Therefore, user fatigue becomes an issue after many repeated uses of a fastener or plurality of fasteners having this design.
The present invention provides for a fastener assembly that allows for an increase in the overall loop tensile strength of a fastener without the need for additional material usage or compromising the application force of the cable tie and avoids a “pawl roll out” failure.